Improvement in screw-spikes for railroads



A. o. & L. DUNN. SCREW SPIKE FOR RAILROADSQ No. 108,986. Patented Nov 8,, 1870.

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aura .%tate$ ALPHEUS O. DUNN ANDISAAG L. DUNN, OF NEW YORK, 'N. Y.

Letters Patent No. 108,986 dated November 8, 1870 antedated October 28, 1870 IMPROVEMENT :IN scREw-sPiKEs FOR RAILROADS.

The Schedule referred to in these Letters Patent and making part of the same.

We, AL'rHEUs 0. Don, and Isaac L. DUXN, both of thecit-y, county, and State of New York, have invented a certain new article of niaimfaoture in Screw-Spikes for Railroads, of which the-t'ollowing is r a specification. 7

Our invention consists inh'aving a new article of manufacture in spikes which has a slightly-tapered ronnd'shank, with one or more spiral ribs slightly tapered or smaller toward its point, and has, at the same time, square-shouldered notches in said ribs extending partially through them,- so that the spike can be driven home with blows of a hammer, and in driving turns around according to its spiral ribs and becomes very-firmly held in the timber, and has considerable friction in the same to withstand great side pressure, and that at the same time the fibers of the timber are allowed to swell into said notches and thereby obstruct, to a large extent, the self-withdrawing of the spike from the timber.

In the drawing- -Ih"ig11i'e 1 reprcsentsa side view of our spike shown driven in au'ailrfiad-tie, which latter is shown bisected to exhibit the posit-ion of its fibers relative to the spike after being placed therein.

. Figure 2 represents a vertical section of the spike,-

to show the form of its ribs.

A represents the head of the spike;

13, the body of its shank 0 (3, its spiral ribs;

1), the shoulder of the shank; and

E, the point of the spike.

The body 15 is made slightly tapering toward the point, sufiicie ntly to fit, cause, and keep nearly the samepressure and friction all over it in-the timber,

The ribs U O are also made of a graduallyrredud ed dimension toward the point of the spike, for the same purpose as that of tapering the body I Toward the upper portion of the, body B we hareformed on these ribs one or more cavities, F, on each,

on the downward side of the ribs, for the purpose of causing and permitting the fibers of the timber having been bent downward, as indicated by the arrows in dotted lines, as is the ease in driving'the spike home, to spring back and straighten and wedge themselves, and obstruct the turning and withdraw ing of the spike to a large extent.

By means of the taper form of the. ribs and shank, the spike is made stronger, is supported and held more firmly in the timber against the side pressure of the rail, and the rain and water more certainly prevented from settling around the shank in the timber, to cause decay of the spike-and timber, than .with the ordinary spike.

Claim.

\Vhatwe claim as our invention is A new article of manufacture in spikes, when the same is of the tapered form on its shank and spiral- 

